The present invention relates to a power drive for electric switchgear, especially protective low-voltage circuit breakers. The power drive is of the general type including a support plate for the drive parts as well as a drive slide extending over an actuating member of the switchgear which projects through a window-like opening of the power drive.
A power drive of the above type is disclosed, for example, in U.S. Pat. No. 3,328,731. The drive slide of the power drive described in the '731 patent is guided on the support plate. The correct alignment of the slide and its window-like opening relative to the actuating member of the switch depends on an accurate positioning and connection of the support plate to the switchgear. However, unavoidable tolerances can lead to a situation in which the drive slide does not axially cooperate with the actuating member, or does not cooperate at all with the actuating member in an area of the opening. As a result, it is possible that the driving forces are not uniformly applied to the actuating member, but can be locally concentrated in an undesirable manner. Premature wear of the cooperating parts or even breaking of the actuating member can occur as a consequence.